1. Field of the Invention
The present disclosure relates to a solid-state light source device, and in more detail, to a solid-state light source device equipped with a semiconductor light emitting element and a wavelength conversion element.
2. Description of the Related Art
In recent years, there has been a demand for solid-state white light sources having a high optical output power to use as a projection light source such as a projector and an automotive headlight. Currently, a discharge lamp such as a high-luminance mercury lamp is available as a light source for the projector, and a lamp such as a halogen lamp is available as a light source for the automotive headlight. However, there are issues that, for example, service times of these devices are relatively short, or luminous efficiencies of the devices are low. To address these issues, as a light source having a high luminous efficiency, attention is being drawn to a light source using a semiconductor light emitting element such as an LED (Light Emitting Diode) and a semiconductor laser (LD: Laser Diode). For example, PTL 1 proposes a solid-state light source device which can emit white light by combining a semiconductor laser diode as a light emitting element and a wavelength converter using a phosphor. The wavelength converter of the solid-state light source device includes stacked layers containing R (Red) and G (Green) phosphors or R, G, and B (Blue) phosphors. High-luminance white light can be obtained from the light source when blue laser light or near-ultraviolet laser light enter the stacked layers.
In the following, with reference to FIG. 18A and FIG. 18B, a configuration of a conventional solid-state light source device is described. The solid-state light source device shown in FIG. 18A is configured with first excitation light source 10, wavelength conversion member 30, and light guide 20. First excitation light source 10 includes laser element 11 which emits excitation light 1 in a blue wavelength region. Wavelength conversion member 30 absorbs excitation light 1 emitted from the first excitation light source 10 and then converts a wavelength of excitation light 1. Wavelength conversion member 30 contains one or more types of phosphors which emit light in a longer wavelength region than that of excitation light 1. Light guide 20 guides excitation light 1 emitted from first excitation light source 10 and emits excitation light 1 to wavelength conversion member 30. Wavelength conversion member 30 shown in FIG. 18B is configured with stacked two layers, one of which consists of red phosphor 31b in resin and the other of which consists of green phosphor 31a in resin. This wavelength conversion member 30 is mounted on output unit 21 in FIG. 18A.